Basic Gil Farming Guide
When starting out, the first way to make Gil is to save all your items you've obtained from killing monsters. First I will start off with the very basics so you can start buying equipment and other things. And then we will get in to greater detail. Please know the the items I lost below are some of the most popular items to farm. Prices will vary on every server, so please check the value and decide for yourself which is the overall best to hunt on your own.
SIGNET / CRYSTALS
Before heading out to hunt, always make sure to get a Signet from Harara, W.W.
World Server : Phoenix
Fire Crystals Auction>Crystals
Stack Price: 5,000G
Current Date: 07/18/13
Dropped Off: Carrion Crow, Goblin Thug, Goblin Digger
Wind Crystals Auction> Crystals
Stack Price : 4,700G
Current Date: 07/18/13
Dropped Off: Bumblebee, Yagudo Acolyte, Yagudo Initiate, Yagudo Scribe
Honey Auction>Food>Ingredients
Stack Price: 8,000G
Current Date: 07/18/13
Dropped Off: Bumblebee, Giant Bee, Killerbee, Digger Wasp, Giddeus Bee
Silk Thread Auction>Materials>Clothcraft
Stack Price: 18,000G
Current Date: 07/18/13
Dropped Off: Crawler, Canyon Crawler, Carnivorous Crawler
Beehive Chip Auction>Materials>Alchemy
Stack Price: 8,000
Current Date: 07/18/13
Dropped Off: Giant Bee, Killer Bee, Digger Wasp, Giddeus Bee
Wild Onion Auction>Food>Ingredients
Stack Price: 25,000G
Current Date: 07/18/13
Dropped Off: Goblin Thug
Silver Beastcoin Auction>Others>Beast-made
Stack Price: 10,000G
Current Date: 07/18/13
Dropped Off: Yagudo Mendicant, Yagudo Persecutor,
NOTORIOUS MONSTER
SPINY SPIPI > Mist Silk Cape
http://wiki.ffxiclopedia.org/wiki/Spiny_Spipi
Location: East Sarutabaruta
Lottery spawn from the Crawlers around I-7 to J-7.
Also may spawn by the river a little north (I/J-6).